无患子皂素无水乙醇提取工艺及提纯方法比较研究

采用无水乙醇对无患子果皮中的皂素进行提取分离。提取工艺研究表明,当固液比为1:6,在50℃,150r/min摇床中提取6 h后,无患子皂素的得率为37.5%。通过向提取液中分别加入丙酮和无水乙醚可将皂素析出分离,皂素得率分别为17.9%和32.0%。丙酮析出分离出的皂素得率较低,但疏松洁白,颗粒较细,纯度为90.5%。无水乙醚析出分离的皂素颜色微黄,颗粒较大,纯度为84.7%,得率高达85.3%,是理想的无患子皂素提纯溶剂。     

米曲霉发酵纯化无患子皂苷的工艺研究

采用微生物发酵法对无患子皂苷水提取液进行纯化.比较了采用自然发酵、接种酵母菌发酵和接种米曲霉发酵纯化无患子皂苷的效果.结果表明,提取液不灭菌,接种米曲霉发酵纯化效果较为明显,优化后的发酵条件为:温度30℃、接种龄12 h、接种量为3％、摇床转速150 r/min,发酵7d后,皂苷含量稍有下降,但皂苷纯度可从48.71％提高到82.47％.米曲霉发酵法明显优于水提醇沉法、絮凝法和正丁醇萃取法.     

热带假丝酵母XYL1在Pichia pastoris中的表达及固定化细胞发酵生产木糖醇

利用克隆获得的具有双重辅酶依赖性的热带假丝酵母xyl1基因,通过表达载体pGAPZB转入巴斯德毕赤酵母X-33,采用海藻酸钙凝胶包埋法固定该重组菌,研究固定化条件下玉米芯水解液的发酵特性,实现对玉米芯等农业废弃物资源的利用。结果表明,转化xyl1基因的巴斯德毕赤酵母X-33的总酶活达到1.64U/mg。固定化细胞的最适发酵条件为pH 6.0、30℃、接种量20%、装液量28%、转速130r/min,木糖醇转化率为37.5%。为生物转化法大规模生产木糖醇以及乙醇提供新的选择途径。     

超声辅助低水比提取无患子皂素工艺过程研究

无患子皂素是一种天然的表面活性剂,具有良好的乳化、分散、发泡、湿润等功效。采用超声波辅助法低水比无患子皂素提取优化工艺为:超声频率20 kHz,超声时间20 min,料液比1∶6,超声功率800 W,提取温度60℃,皂素提取得率为37.27%。超声波辅助法提取无患子皂素可以减少过程用水量,降低能耗,提高皂素得率。     

假丝酵母发酵玉米芯半纤维素水解液生产木糖醇

采用一株驯化过的假丝酵母(Candida sp.)直接发酵经过简单脱毒处理的玉米芯半纤维素水解液生产木糖醇。确定了水解液的最适浓缩倍数在3.0～3.72的范围内。利用正交实验,确定了摇瓶分批发酵工艺条件的最适组合为：摇床转速180r/min,起始C/N为50,起始pH 5.5,接种量5% (体积比)。在此基础上,重点研究了在发酵罐中通气量对酵母发酵玉米芯水解液生产木糖醇的影响。结果表明采用先高后低的分段通气发酵在木糖醇得率方面明显优于恒定通气发酵;其中,在0～24h,3.75 L/min;24～108h,1.25 L/min的分段通气条件下(装液量为2.5L),木糖醇得率(木糖醇/木糖,g/g) 达到0.75 g/g。该结果将有助于建立一种高效的、大规模的利用玉米芯半纤维素水解液发酵生产木糖醇的工艺。     

利用杨木水解液制备细菌纤维素

选用杨木木屑水解液为发酵基质,利用木醋杆菌发酵制备细菌纤维素。研究还原糖浓度、初始p H值、接种量、发酵温度和发酵时间对细菌纤维素产量、持水性和复水率的影响。结果表明,生产细菌纤维素的适宜条件为:杨木木屑水解液还原糖浓度为2.5%,初始p H为6.0,接种量为6%,发酵时间6 d,发酵温度30℃,在此条件下,细菌纤维素产量为3.14 g/L,持水性为98.72%,复水率为86.69%。采用扫描电镜、红外光谱、热失重分析法等技术分析了所制备的细菌纤维素的结构与性能,结果表明合成产物为超微细网状结构,且产物中含有的基团与纤维素结构相符合。     

聚氨酯固定化热带假丝酵母发酵木糖醇

固定在多孔聚氨酯载体中的热带假丝酵母(Candida tropicalis), 可有效地利用玉米芯半纤维素水解液生产木糖醇。在摇瓶条件下, 采用分批发酵方式, 确立了适宜的发酵工艺参数为: 接种量7%, 聚氨酯加入量1.0 g/100 mL, 温度30°C, 初始pH值6.0, 分段改变摇床转速进行溶氧调节, 其中0~24 h 为200 r/min; 24 h~46 h为140 r/min。聚氨酯固定化提高了菌体对发酵抑制物的耐受力, 固定化细胞密度高, 发酵性能稳定, 发酵产率和体积生产速率都有所提高。水解液未经脱色与离子交换便可转化成木糖醇, 大幅降低了成本, 显示了良好的应用前景。固定化细胞连续重复进行12批次21 d的发酵, 木糖醇得率平均为67.6%, 体积生产速率平均为1.92 g/(L·h)。     

混合菌群发酵秸秆合成菌体蛋白及其动力学分析

混合菌群发酵秸秆可有效提高秸秆纤维的降解率及菌体蛋白的转化率,对拓广蛋白饲料来源、减少环境污染起到积极的作用。本研究以小麦秸秆为原料,在纤维素酶水解预处理的基础上,以米曲霉作为先导菌,进一步分解残留的粗纤维,为后期发酵提供充足的碳源。根据不同微生物的代谢特征和协同机理,试验确定了发酵阶段混合菌群的组成为:米曲霉、产朊假丝酵母和枯草芽胞杆菌;接种顺序为:先接种米曲霉,再接种产朊假丝酵母,最后接种枯草芽胞杆菌。正交试验表明,影响发酵主要因素的主次顺序为:秸秆与麸皮配比>接种比例>发酵时间>接种量>发酵温度;发酵的最适条件为:米曲霉的接种量2.5%,发酵12h后接入5%的产朊假丝酵母,继续发酵8h后接入2.5%的枯草芽胞杆菌,发酵温度为28℃,秸秆与麸皮的配比为4∶1,尿素添加量为1.2%;结合动力学分析,将混合菌群的发酵时间优化为35h,发酵产物中粗蛋白含量由原来的5.47%提高到25%左右。对最适发酵条件下的动力学过程进行了探讨,建立了以Logistic方程为基础的数学模型和动力学方程。本研究表明,混合菌群发酵秸秆提高了发酵产物中的粗蛋白含量。动力学分析对于了解发酵机理、掌握整个发酵过程中混合菌群生长的动态变化、优化发酵工艺具有重要的指导意义。     

利用废水液体发酵生产单细胞蛋白的实验研究

利用工厂废水或动物血制作培养基,以液体发酵方式培养产朊假丝酵母NCTC3576菌及甘饲8501菌.离心分离菌体,测定菌体生物生长量,并观察蔗糖、温度、酸碱度、发酵时间、种子液接种量对生物生长量的影响.生化方法分析NCTC3576菌单细胞蛋白的品质,氨基酸分析仪分析单细胞蛋白的氨基酸组成.结果表明,玉米淀粉厂废水,不必调pH,不用添加其它任何组分,即可直接用于液体发酵产朊假丝酵母NCTC3576菌;pH4.0～7.0均对生长量无明显影响;24h培养已达到最好生长量,再延长时间已不能提高产量;28℃及37℃培养无明显差别,在3%～17%种子液接种量范围内,接种量与生长量有正相关关系.研究表明,玉米淀粉厂废水单一成分即可用于液体发酵产朊假丝酵母NCTC3576菌,原料成本低,且易于产品分离纯化和工业化生产中的连续培养,是单细胞蛋白生产的良好途径.     

粗壮假丝酵母(Candida valida 20231)产脂肪酶发酵条件的研究

对粗壮假丝酵母(Candida valida 20231)产脂肪酶所需的培养基成分和发酵条件进行了优化。结果表明,粗壮假丝酵母在接种后3 h即进入对数期,18 h后转入稳定期,66 h后进入衰退期;发酵36 h达到最大酶活,至72 h仍然无明显下降趋势。最适合的培养基成分为:4.0%大豆粉,2.0%菜籽油,0.3%葡萄糖,0.3%NH_4NO_3,1.2%K_2HPO_4,0.42%NaH_2PO_4,0.4%MgSO_4·7H_2O。使用优化的培养基,最佳产酶的条件为:装液量80 mL(250 mL摇瓶),初始pH 6,接种量为2.0%,种子菌龄为12 h。在最佳产酶条件下,脂肪酶活力达到32.6 U/mL。     

从脱毒棉籽粕和食用菌中提取食用核酸的工艺探讨

目的：利用核酸含量高的植物原料,探索食用核酸提取新工艺。方法：以脱毒棉籽粕粉和平菇子实体为原料,采用去离子水一次抽提-等电点与乙醇分次沉析法和NaCl溶液分次抽提-等电点与乙醇一次沉析法从中提取核酸。结果：两种原料采用两种不同工艺,提取核酸制品的A260／A280值均大于1．6,其中水提法大于1．6,盐提法大于1．8。核酸提取率在1．0％以上,其中水提法为1．07％和2．05％,盐提法为1．74％和2．48％。结论：脱毒棉籽粕粉和平菇子实体均是提取核酸的良好原料,后者优于前者。水提法和盐提法均适合于对脱毒棉籽粕粉和平菇子实体中食用核酸的提取,盐提法更为合理。     

正交试验法优化桑叶多糖提取工艺

以脱除黄酮的桑叶为原料,采用热水浸提法提取桑叶多糖,研究了提取温度、提取时间、料液比、水溶液pH和提取次数对桑叶多糖得率的影响,通过正交实验优化了提取工艺条件。结果表明,在提取次数为2次条件下,桑叶多糖最佳提取工艺条件为提取温度100℃、提取时间4 h、提取液pH7、料液比(原料:提取液,g/mL)1:30,多糖得率为2.74%。该工艺稳定,桑叶多糖得率高,易于工业化生产。     

Production of highly concentrated ethanol in a coupled fermentation/pervaporation process using silicalite membranes

The fermentation performance of a coupled fermentation/pervaporation process using silicalite membranes, which are ethanol permselective for an ethanol/water solution, was studied. The process exhibited about a 20% increase in an average glucose consumption rate as compared with that without the pervaporation unit. A strong correlation was observed between the membrane flux and the consumption rate. Ethanol concentrations in the permeates reached a maximum of 85% (v/v).     

ATP- and calcium-controlled contraction in a saponin model of Physarum polycephalum

Saponin models of the plasmodial strand of Physarum polycephalum were constructed to study how Ca2+ and ATP regulate the generation of tension. ATP-induced isometric tension in a saponin model increased with an increase in ATP concentration until maximum tension (0.3-1.7 mg) was reached at about 1 mM. The sensitivity of the model to ATP was heightened three to five times in a basic solution containing an ATP-regenerating system, the maximum tension (0.3-0.6 mg) being reached at 0.2 to 0.3 mM ATP. Contraction of the model also depended on the Ca2+ concentration irrespective of the presence or absence of the ATP-regenerating system. The optimal pCa was 7.0, and tension decreased with a Ca2+ concentration above or below this value. These results indicate that the tension generated in the plasmodial strand of Physarum in vivo may be regulated by ATP and/or Ca2+.     

Aqueous two-phase extraction of 2,3-butanediol from fermentation broths using an ethanol/phosphate system

Separation of 2,3-butanediol from the complex fermentation broths is a difficult task and becomes a bottleneck in industrial production. Aqueous two-phase systems composed of hydrophilic solvents and inorganic salts could be used to extract 2,3-butanediol from fermentation broths. Aqueous two-phase extraction of 2,3-butanediol from fermentation broths was studied by ethanol and dipotassium hydrogen phosphate system. The influences of phase composition on partition of 2,3-butanediol, removal of cells and biomacromolecules were investigated. The partition coefficient and recovery of 2,3-butanediol reached up to 28.34 and 98.13%, respectively, and the selective coefficient of 2,3-butanediol to glucose was 615.87 when the system was composed of 24% (w/w) ethanol and 25% (w/w) dipotassium hydrogen phosphate. Simultaneously, cells and proteins could be removed from the fermentation broths and the removal ratio reached 99.63 and 85.9%, respectively. This process is convenient and economic, furthermore, the operation is easy to scale-up, that is, this method provides a new possibility for the separation and refining of 2,3-butanediol.     

Mixed substrate solid state fermentation for production and extraction of lipase from Aspergillus niger MTCC 2594

A novel mixed substrate solid-state fermentation (SSF) process has been developed for Aspergillus niger MTCC 2594 using wheat bran (WB) and gingelly oil cake (GOC) and the results showed that addition of GOC to WB (WB : GOC, 3 : 1, w/w) increased the lipase activity by 36.0% and the activity was 384.3+/-4.5 U/g dry substrate at 30 degrees C and 72 h. Scale up of lipase production to 100 g and 1 kg tray-level batch fermentation resulted in 95.0% and 84.0% of enzyme activities respectively at 72 h. A three-stage multiple contact counter-current extraction yielded 97% enzyme recovery with a contact time of 60 min. However, extraction by simple percolation and plug-flow methods resulted in decreased enzyme recoveries. The mixed substrate SSF process has resulted in a significant increase in specific activity (58.9%) when compared to a submerged fermentation (SmF) system. Furthermore, an efficient process of extraction has been standardized with this process. Use of GOC along with WB as potential raw materials for enzyme production could be of great commercial significance. This is the first report on the production and extraction of lipase from Aspergillus niger using mixed solid substrates, WB and GOC, which are potential raw materials for the production of enzymes and other value-added products.     

Acetone-butanol-ethanol fermentation and isoflavone extraction using kudzu roots

The economics of Acetone-butanol-ethanol (ABE) fermentation is greatly affected by raw materials, and the use of readily available starchy materials from marginal farming lands could be a viable option for reducing costs. Kudzu, a rapidly growing perennial leguminous vine, has been planted on marginal farming land and widely distributed in Asia and America. This study investigated ABE fermentation by C. acetobutylicum ATCC 824 using kudzu roots and isoflavone extraction from kudzu fermentation residue (KFR). The kudzu roots could be used as a sole substrate for ABE fermentation without nutritional supplements. Batch culture containing 140 g kudzu/L produced 17.99 ± 1.08 g/L solvent (ABE), including 11.20 ± 0.79 g/L butanol, 5.54 ± 0.20 g/L acetone, and 1.15 ± 0.09 g/L ethanol, with a productivity of 0.19 g/(L/h) and a yield of 0.33 g solvent/g sugar after 96 h of fermentation. Isoflavone yield extracted from KFR was 1.90/100 g KFR, approximately 48% higher compared with that extracted from raw kudzu. A kinetic analysis of the extraction process showed that both the isoflavone yield and the extraction rate obtained from KFR were higher than the corresponding values obtained from raw kudzu. These results indicate that kudzu may provide a new potential raw material for ABE production and the process of ABE fermentation integrated with isoflavone extraction may provide a new way to reduce fermentable substrate costs.     

以糙米为原料流加L-蛋氨酸的S-腺苷蛋氨酸发酵优化

研究了S-腺苷甲硫氨酸(SAM)高产菌啤酒酵母S-W55的廉价培养基及分批补料发酵过程优化.对啤酒酵母S-W55生长和SAM产量影响最为重要的糙米水解糖和酵母粉进行了响应面优化,得到了最优化的配方为糙米水解糖51.4g/L、酵母粉4.74g/L,此条件下啤酒酵母S-W55的SAM产量达2.61 g/L.不同分批补料发酵...     

水蒸气蒸馏法提取大蒜挥发油的工艺研究

以挥发油提取率为指标,通过单因素和L9(34)正交试验设计确定了水蒸气蒸馏法提取大蒜挥发油的最佳提取工艺及条件。结果表明,各因素作用主次顺序为蒸馏时间(D)>料液比(C)>发酵温度(A)>浸泡时间(B),各因子的最优组合为A2B2C2D3,即以1∶3.5的料液比(m∶V),在35℃时浸泡3h后蒸馏2h为大蒜挥发油的最佳提取工艺,此时挥发油的提取率达到0.32%,证明此方法是大蒜挥发油提取的可靠、易行的科学方法。     

H_2O_2预处理结合微生物发酵提取玉米芯木聚糖的工艺研究

为提高微生物发酵玉米芯提取木聚糖的效率,本研究采用H2O2预处理结合微生物发酵的方法提取玉米芯中的木聚糖,并通过扫描电镜(SEM)从微观结构初步探讨了H2O2预处理提高微生物发酵提取玉米芯木聚糖的原因。其结果表明:利用4%H2O2预处理玉米芯1小时,木聚糖含量可达40. 21±0. 21 mg/g,较未处理组玉米芯中木聚糖含量提高了87. 72%;4%H2O2预处理结合微生物发酵玉米芯,可显著提高木聚糖得率,其含量可达52. 72 mg/g,较未经H2O2预处理组提高了186. 67%;进一步利用响应面法优化微生物发酵经H2O2预处理玉米芯提取木聚糖的工艺,得到了发酵最佳培养基组成为含水量50%、尿素添加量0. 25%、葡萄糖添加量0. 75%,此条件下木聚糖含量达70. 84 mg/g,较未发酵提高了249. 82%;SEM图像显示H2O2预处理使得玉米芯结构变得疏松,微生物发酵结合H2O2预处理后的玉米芯出现较大孔洞,结构变得更为疏松。因此,H2O2预处理可改善玉米芯结构,促进微生物发酵,提高玉米芯木聚糖的提取效率,为玉米芯木聚糖的高效开发利用提供了参考。